Water under high pressure is used for various purposes. High pressure water is used in high pressure streams of water in fluid blast systems for cleaning purposes. Such high pressure systems are used for cleaning surfaces and for cleaning unwanted coatings or deposits off surfaces of various types particularly metal and concrete surfaces. In addition, it is well known to use water at high pressure for cleaning the interior surfaces of vessels and tubes particularly to remove scale and other deposits.
In the prior art, fluid systems are provided in which a high pressure stream of water is ejected at very high speeds. It is known that even a relatively small volume of water travelling at such a high speed, as an example, 800 feet per second, is capable of transferring tremendous momentum and is therefore extremely dangerous to human beings located within a short range of the cleaning lance or apparatus.
It is also well known that it is necessary for the operator of the high pressure water cleaning lance to be able to quickly reduce the velocity of the water issuing therefrom. The problems of the prior art and one solution is described in U.S. Pat. No. 3,672,575, issued Jun. 27, 1972, to Jack F. Hinrichs.
The cleaning lances of the prior art have certain disadvantages. In some devices because of the great pressure involved, the mechanical force required to depress the handle lever or trigger is so great that it makes the depression of the lever tiresome and therefore reduces the operating time of the nozzle. In addition, because of the high pressures involved, the cleaning lances of the prior art in certain cases leak after a relatively short period of use.
The present invention is designed and constructed for operator comfort and ease of operation in applications involving water pressures up to 40,000 psi. In addition, the novel lance weighs only 11 lbs. approximately vs. 17 lbs. for some prior art devices, making it easy to control and to operate for extended periods.